(a) Field of the Invention
The present invention relates to a method for handover in a wireless communication system using multiple carriers.
(b) Description of the Related Art
At present, an international mobile telecommunication (IMT)-Advanced system allows for higher data transfer rate, and enables one terminal to get more integrated services at a time. The integrated services, like a quadruple play service (QPS), may include internet telephone service, high-speed interactive service, large data transfer, mobility IP-TV, and so on.
To this end, it is recommended that an IMT-Advanced system uses a wide range of frequency from 400 MHz to 4 GHz. On the basis of this frequency band, one cell (or base station) in a wireless communication system can operate with a multi-component carrier for wider bandwidth.
However, in a cell that operates with multiple carriers in 3rd generation partnership project long term evolution (3GPP LTE) or institute of electrical and electronics engineers (IEEE) 16m, each carrier may have a different cell coverage according to frequency characteristics, such as bandwidth/duplex distance, or user policies, such as the number of operational carriers. As a result, a contiguous connection between adjacent cells is not provided but communication between cells may be interrupted, or data forwarding between carriers of a serving cell and a target cell cannot be performed in a handover step, thereby failing to perform a normal handover.
The above information disclosed in this Background section is only for enhancement of understanding of the background of the invention and therefore it may contain information that does not form the prior art that is already known in this country to a person of ordinary skill in the art.